Physics Midterm Review Sheet

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Physics Midterm Review Sheet

The test comprises of

 ~ 65 multiple choice questions

 2-4 short answer … less than 1 page each with diagrams)

KNOW YOUR UNITS

 kg  mass

 meter (m), km, ft, mile, inch  distance

 meter/second (m/s), mph, km/hr  speed / velocity

 meter/second

2

(m/s

2

, m/s/s)

 acceleration

Newton (N) = kg*m/s

2  force

 Basic scientific notation ( if something is correctly written )

 Basic significant figures ( how many a number has )

Kinematics

 Distance is total length traveled

 Displacement is difference form beginning to end point o With no acceleration:

 x = v*t o With acceleration:

 x = v*t + 1/2 a*t

2 o Need to know relation, not really the math.

 Velocity (speed) = change in displacement / change in time o V average

=

 x / t o Know relation and maybe simple problem with equation

 Acceleration = change in velocity / change in time o A average

=

 v / t o Know relation and maybe simple problem with equation

Graphical Analysis of Motion

 KNOW what graphs of different types of motion look like

(both d vs. t and v vs. t graphs) {mini-graphs} o Zero velocity o Constant velocity o Accelerated motion

 Slope of “position – time graph” is velocity

Slope of “velocity – time graph” is acceleration

 Area under “velocity – time” graph is displacement

Vectors

Have magnitude (size) and direction

 Are added by placing them head to tail

 Can be thought of in components

 Basic Sine, cosine, tangent  SOH-CAH-TOA

Basic adding of them in 1 dimension o i.e., 40 right and 10 left equals 30 right. o 10 N up and 3 N down equals 7 N up.

Projectile Motion

 A projectile is an object where the only force acting is gravity

 All objects fall with same acceleration that never changes o On Earth g = 9.8 m/s

2

, on Moon it is about 1.6 m/s

2

A projectile’s horizontal velocity is constant

A projectile’s vertical velocity continuously increases in the negative direction. o Slows down when going up o Speeds up when going down

 At top of projectile path, V yo

= 0

 X-displacement [

 x= velocity * time] so each second object travels the same distance horizontally

 Y-displacement [

 y = V yo

*t – ½*g*t

2

], so each second object falls a greater distance than the previous second.

 45° shot angle gives maximum range (X)

Forces

Newton’s Laws o 1: Law of Inertia:

(increase) mass means

(increase) inertia

 object in motion wants to stay in motion, object at rest wants to stay at rest. o 2: F=m*a  to have acceleration there must be a net force, and if there is a net force, there will be acceleration

 

F  

a;

m  

a o 3: Action – Reaction: forces always act in equal magnitude/opposite direction pairs

Net Force = mass*acceleration **

F = m*a o constant velocity or at rest = NO net force o changing velocity = YES net force

 Net force = sum of forces taking into account direction o 10 N left and 30 N right; F net

= 30-10 = 20N o 20 N up and 10 N up; F net

= 20 + 10 = 30 N

 Weight = mass * acceleration of gravity ** F g

= m*g

F f

=

*F

N

Momentum (pre read in book Chapter 7 pp. 86-98)

 Momentum = mass * velocity

Impulse = Force * time o Increase impact time decreases impact force

 Impulse-Momentum Theorem

 Impulse = change in momentum, J =

 p

In a collision, momentum is conserved

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